Request Token Lookup Fail

[thunkele]

This randomly started happening to my application. There doesn't seem to be a pattern, but the request token lookup fails sporadically on production (this record does exist in the table). I have 40k + keys in the table, not sure if that might be causing the issue. Has anyone come across this?

Started GET "/oauth/authorize?oauth_token=vrd2pfnPoZEiLwvz6zIM0VSQpUnms6hoZoX5MAP2" for xxx.xxx.xxx.xxx at Wed Sep 26 11:41:13 +0000 2012
Processing by OauthController#authorize as HTML
Parameters: {"oauth_token"=>"vrd2pfnPoZEiLwvz6zIM0VSQpUnms6hoZoX5MAP2"}
Completed 500 Internal Server Error in 15ms

ActiveRecord::RecordNotFound (Couldn't find RequestToken with token = vrd2pfnPoZEiLwvz6zIM0VSQpUnms6hoZoX5MAP2):